1. Field of the Invention
This invention relates to joints between elements, such as building panels, and more particularly to polysurfaced male and female lips which are interlocked to provide an upstanding joint.
2. Description of the Prior Art
The prior art discloses numerous examples of joints which secure together adjacent sheet metal panels without the necessity of crimping or otherwise deforming the elements of the joint. Typical examples include U.S. Pat. Nos. 2,019,379 (ANDERSON); 3,127,962 (JAMES); 3,481,094 (TAYLOR); 3,511,011 (STRAUS).
The ANDERSON joint is particularly suited for use in connecting the slats of a rolling metal curtain. When used in wall or roof structures, the male lip may be partially disengaged from the female lip by loads applied at locations adjacent to the male lip. The possible partial disengagement precludes formation of a reliable weather-tight seal.
The JAMES joint avoids the partial disengagement problem by providing tightly nested cylindrically-shaped connecting members. A lubricant must be applied to the contacting surfaces of the connecting members to facilitate interconnection. The cylindrically-shaped connecting members have substantially identical girths and therefore appear to utilize more material than is actually necessary.
The TAYLOR joint also attempts to avoid the partial disengagement problem discussed above by providing an inwardly extending crimp on the female lip which is engaged by the terminal edge of the male lip. Despite the presence of the crimp, the male lip is still subject to deflection by applied loads and degradation of the weather-tight seal.
The STRAUS joint utilizes intricately formed male and female lips of single and double metal thickness, respectively. The female lip is particularly subject to damage during packaging, shipment and erection. Such damage would interfere with the interconnection of the lips and the formation of a weather-tight seal.